func (s *EtcdV3Storage) Watch(ctx context.Context, key string) <-chan WatchResponse { 
 	eventChan := Client.Watch(ctx, key, clientv3.WithPrefix()) 
 	ch := make(chan WatchResponse, 1) 
 	go func() { 
 		for event := range eventChan { 
 			output := WatchResponse{ 
 				Canceled: event.Canceled, 
 			} 
  
 			for i := range event.Events { 
 				e := Event{ 
 					Key:   string(event.Events[i].Kv.Key), 
 					Value: string(event.Events[i].Kv.Value), 
 				} 
 				switch event.Events[i].Type { 
 				case clientv3.EventTypePut: 
 					e.Type = EventTypePut 
 				case clientv3.EventTypeDelete: 
 					e.Type = EventTypeDelete 
 				} 
 				output.Events = append(output.Events, e) 
 			} 
 			if output.Canceled { 
 				output.Error = fmt.Errorf("channel canceled") 
 			} 
 			ch <- output 
 		} 
              
                close(ch)
 	}() 
  
 	return ch 
 }